Polyalkylene oxides stabilized with an amine and an aliphatic thioether



United States Patent 1 Claim. (CL, 260-45.8)

ABSTRACT OF THE DISCLOSURE 1 Polyalkylene oxides stabilized with a mixture of an amine and an aliphatic thioether.

The present invention relates to stabilized polyalkylene oxides and a process for preparing them.

It is known that homoand copolymers of alkylene oxides, like all polyethers, are liable to degradation reactions to a greater or smaller extent at raised temperatures and under the .action of oxygen and light and, therefore, must be stabilized prior to being processed or used.

It has already been proposed to use as stabilizers, for example for polypropylene oxide, aromatic amines or phenols. However, stabilizers of this type are little effective, especially when the polymers are processed above 100 C. and they do not inhibit degradation at higher temperatures-for example at 110 C.

It has now been found that a mixture of mula R--S R' in which n stands for a whole number in the range of from 1 to 4, R and R represent an alkyl radical with 8- 20 carbon atoms or the group (CH COOR in the latter group m being a whole number in the range of from 1 to 4 and R an alkylene radical with 8-20 carbon atoms, is excellently suitable for stabilizing polyalkylene oxides. The aforesaid radicals R and R may be identical or different. The mixing ratio of components a and b is preferably in the range of from 1:5 to :1 parts by weight.

As known amine stabilizers there are mentioned by way of example: aliphatic amines substituted by aromatic radicals such as N,N-diphenyl-ethylene diamine, heterocyclic amines such as phenothiazine; and aromatic amines. It is particularly advantageous to use aromatic amines having 12-30 carbon atoms and 1-3 nitrogen atoms in the molecule, for example phenyl-fi-naphthylamine, 4,4- F

diamino-diphenylamine, N,N-diphenyl-ethylene diamine, N-cyclohexyl-N'-phenyl-p-phenylene diamine, N,N'-dicyclohexyl-p-phenylene diamine, N,N-diisopropyl-p-phenylene diamine, N,N-dioctyl-p-phenylene diamine and N,N' didodecyl-p-phenylene diamine.

As organic sulphur compounds enter into consideration, for example:

Di(dodecyl)sulfide, di(octadecyl)sulfide, di(dodecyl) disulfide, di(octadecyl)disulfide, di(dodecyl)trisulfide, di (octadecyl)trisulfide, di(dodecyl)tetrasulfide, di(octadecyl)tetrasulfide, thio-diglycolic acid dodecyl ester, thiodipropionic acid octadecyl ester, thiodibutyric acid dodecyl ester, dithiodiacetic acid dodecyl ester, dithiodipropionic acid dodecyl ester, trisulfide(diacetic acid octadecyl ester), tetrasulfide(diacetic acid octadecyl ester) and the like.

In order to obtain a good stabilizing effect the aforesaid stabilizer mixtures are preferably used in an amount of 0.3-3%, calculated on the weight of the polyalkylene oxide and intimately mixed with the polyalkylene oxide. Of course, mixtures of polymers may be stabilized, too. The stabilizer mixtures are added in solid form or in the form of a solution, advantageously during processing of the polymerization product directly after having carried out the polymerization process. It is likewise possible, however, to add the stabilizers to the solid polymer after processing. Mixing is preferably performed with the exclusion of air by rolling on a multiple roller mill as used, for example, in rubber industries or in a suitable kneader or extruder.

Polymers that can be stabilized by the process of the invention are homoand copolymers of alkylene oxides. The homoand copolymers are produced by polymerizing saturated alkylene oxides, such as for example, ethylene oxide, propylene oxide and isobutylene oxide, furthermore substituted epoxides such as, for example, epichlorohydrin, perfluoro-propylene oxide and 1-chloro-3,4-epoxybutane; cycloaliphatic epoxides such as cyclohexene oxide; epoxy ethers such as methyland phenylglycidyl ethers; or by copolymerization of unsaturated with saturated epoxides such as, for example, allylglycidyl ether, o-allylphenylglycidyl ether, glycidyl acrylate, vinylcyclohexene monoepoxide, cyclohexene oxide, butadiene monoxide, and 1,2-epoxycyclooctene-(5), in the presence of known ioniccatalysts. Especially good results are obtained with the copolymerization of saturated and unsaturated alkylene oxides when the stabilization is carried out before they have been cross-linked, that is to say directly after polymerization. The stabilized polymers thus obtained are of crystalline, amorphous or rubber-like consistency. To test the compounds used according to the invention as to their stabilizing effect the following method was applied:

The stabilizer dissolved in benzene was added to a benzenic solution of the polyalkylene oxide or the copolymer. The solution was thoroughly mixed and a film was prepared by evaporating the benzene. The film was heattreated at C. in a drying cabinet with the access of air. At intervals of 24 hours samples were taken, a 0.1% benzenic solution was prepared and the reduced specific viscosity was determined at 25 C. The reduction of the reduced specific viscosity is a measurement of the oxidative degradation of the polymer.

The following examples serve to illustrate the invention but they are not intended to limit it thereto.

The examples are summarized in the form of a table and illustrate the effectiveness of the stabilizers to be used according to the invention. The stabilizer effect was determined with a copolymer of propylene oxide and 1,2- epoxy-cyclooctene-(S) and a copolymer of propylene oxide and allylglycidyl ether. The films were heat-treated at 110 C. Example 1 in Table 1 shows the behavior of the unstabilized copolymers while Examples 2-10 and 21- 25 of Tables 1 and 3 demonstrate the stabilizing effect of the individual components of the mixtures to be used according to the invention. Examples ll-20 of Tables 2 and 3 show the stabilizing effect of the mixtures to be used.

A comparison of Example 2 (Table 1) with Examples 12, 13 and 14- (Table 2) shows that the measuring data of the reduced specific viscosity of the mixtures with identi-"' cal concentration are higher than the values of the reduced specific viscosity of the individual components. Moreover, the mixtures have a considerably prolonged 4 amine, N,N'-dioctyl-p-phenylene diamine and N,N-di dodecyl-p-phenylene diamine and (b) an aliphatic thioether of the formula RS R' in which It stands for a whole number in the range from stabilizing effect as compared with the individual compo- 5 1 to 4 R and R represent a member selected from the nents. The same phenomena can be observed with the cogroup consisting of an alkyl radical with 8 to 20 carbon polymer of propylene oxide and allylglycidyl ether (Table atoms and the group --(CH COOR in said group I m being a whole number in the range of 1 to 4 and R Hence, it follows that with the combination of the being an alkyl radical with 8m 20 carbon atoms, comtWo components an unexpected and very pronounced syn- 10 ponents (a) and (13) being contained in the mixture withergistic effect occurs. in the range of 1:5 to 5:1 parts by weight.

TABLE 1 Stabilizer concentra- Initial After After After After After After After N0. Stabilizers tion in value, 1 day, 2 days, 3 days, 6 days, 12 days, 18 days, 22 days,

percent by 711'Bd red nred nred 111'9 red red rcd weight Without stabilizer 16. 1 Phenyl-B-naphthylamine 1 15.8 11. 10. 1 N gihenyl-N-cyclohexyl-p-phenylene famine 1 15. 9 11. 0 8. 6 N,N-di-fl-naphthylp-phenylene diamine 1 15. 8 11.3 9. 8 Di(octadecyl) sulfide 1 16. 0 3.3 0.1 Di(octadecyl) disulfide. 1 15. 7 5. 2 1. 6 Di(octadecyl) trisu1fide 1 16.1 5. 6 0.7 Di(octadecyl) tetrasulfide 1 15.9 7.2 2.1 Tn'sulfide (diacetic acid octadecyl ester) 1 15. 7 7. 1 3. 8 Thio-dipropionic acid dodecyl ester 1 15. 9 7. 2 2. 5

TABLE 2 Stabilizer cencentra- Initial After- After After After After After After After After N0. Stabilizers tion in value, 1 2 3 6 12 18 22 25 28 percent by :1 red day, days, days, days, days, days, days, days, days, weight 1 red 1 redj 1 red 1 red '7 red 1, red 1, red 1, red 1, red

Phenyl-B-naphthylamine 0. 5 gl l fi t gl r g 15. 7 12. 0 10. 5 9. 1 7. 1 5. 2 4. 1 3. 2 2. 1

eny map y amine glg l fiii l w 16.0 12.3 10.7 10.5 10.0 5.7 4.7 8.0 2.9 1.2

eny -fi-nap y amine gt f l fi fi 5 15.8 12.5 10.5 10.3 10.0 7.6 5.3 4. e 3.1 1.5

eny -,8-nap t ylamine .5 Dfloctadecyl)tetrasulfide 5 16.1 12.2 11.2 10.9 10.2 7.3 5.6 4.7 3.3 1.5 N-phenylrN-cyclohexyl-p-phenylendiamine 0. 5 16. 0 12. 3 11. 5 10. 5 10. 0 6. 9 5. 3 4. 1 3. 3 1. 3 Trisulfide (diacetic acid octadecyl ester) 0. 5 16 N,Ndi-1S-11aphthyl-p-phenylene dia- Z,

' mine .Q. O. 5 15. 8 12. 0 11. 1 10. 1 9. 8 5. 9 4. 9 3. 7 2. 9 0. 9

Thio-dipropionic acid dodecyl ester 0.5

TABLE 3 Stabilizer cencentra- Initial After After After After After After After After After No. Stabilizers tion in value, 1 2 3 4 18 22 30 percent by 1 red day. days, days, days, days, days, days, days, days, Weight 1 red 1; red 1 red 1 red 1; red 7 red 1; red 1 red n red 17 N,N-didodecyl-p-phcnylenediamine 0.5 I 18 g g g g i g f H h 5 14.2 11.9 11.1 10.0

i o ecy -p-p eny ene iamine 0.5 1 gigcitlldlecgbtrlisulf'ilde .5

9 i 0 ecy -p-p eny ene iamine .5

gflNoctttetglhetrasillllfidelua 0.5 l

i o ecy-p-p eny ene iarnine 0.5 Thio-dipropionic acid dodecyl ester. 0.5 i 5 6 2 6 N,N -didodecyl-p-phenyldiamine. 1. 0 14. 4 11. 0 10. 3 8. 2 Di(octadecyl)disu lfide 1. 0 14. 6 5. 1 3. 6 1. 7 Di(octadecyl)trisulfide 1. 0 14. 5 5. 9 3. 9 1, 7 Di(octadecy1)tetrasulfide 1.0 14. 6 6. 8 5.0 2. 8 I Thio-dipropionic acid dodecyl ester 1.0 14. 3 5. 1 3. 4 1. 4

We claimi i 65 References Cited 1 60115138551131; of 1mattterd comtplrismg it pclyt iallkylefe UNITED STATES PATENTS OX1 8 an 0 C8. 011-3. 6 on 6 Welg 0 e PO yalkylene oxide of a mixture comprising (a) an amine se- 2920059 1/1960 MacDonald et 26O 45'9 lected fromthe group consisting of N,N-diphenyl-ethyl- 311331896 5/1964 F et -85 ene diamine, phenothiazine, N,-N.-di-B-naphthyl-pphen- 7 3,277,044 10/1966' Welssefmel et 26-0453 ylene amine, phenyl-fi-naphthylamine, 4,4'-diamino-diphenylamine, N,N-diphenyl-ethylene diamine, N-cyclohexyl-N'-phenyl-p-phenylene diamine, N,N -dicyclohexylp-phenyleue diamine, N,N'diisopropyl-p-phenylene di- DONALD E. CZAJA Primary Examiner, V. P. HOKE,'Assistg.nt Examiner. 

